• The Korean Journal of Physiology and Pharmacology
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• 제20권3호
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• pp.297-304
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• 2016

Klotho functions as a tumor suppressor predominantly expressed in renal tubular cells, the origin of clear cell renal cell carcinoma (ccRCC). Altered expression and/or activity of growth factor receptor have been implicated in ccRCC development. Although Klotho suppresses a tumor progression through growth factor receptor signaling including insulin-like growth factor-1 receptor (IGF-1R), the role of Klotho acting on IGF-1R in ccRCC and its clinical relevance remains obscure. Here, we show that Klotho is favorable prognostic factor for ccRCC and exerts tumor suppressive role for ccRCC through inhibiting IGF-1R signaling. Our data shows the following key findings. First, in tumor tissues, the level of Klotho and IGF-1R expression are low or high, respectively, compared to that of adjacent non-neoplastic parenchyma. Second, the Klotho expression is clearly low in higher grade of ccRCC and is closely associated with clinical outcomes in tumor progression. Third, Klotho suppresses IGF-1-stimulated cell proliferation and migration by inhibiting PI3K/Akt pathway. These results provide compelling evidence supporting that Klotho acting on IGF-1R signaling functions as tumor suppressor in ccRCC and suggest that Klotho is a potential carcinostatis substance for ccRCC.

• Transactions on Electrical and Electronic Materials
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• 제11권3호
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• pp.126-129
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• 2010

(1-X) $(Na_{0.5}K_{0.5})NbO_3-X$ $K_4CuNb_8O_{23}$ (NKN-X KCN) ceramics were produced using the conventional solid state sintering method, and their sinterability and electric properties were investigated. The density, dielectric constant (${\varepsilon}_r$), piezoelectric constant $d_{33}$, electromechanical coupling factor $k_p$ and mechanical quality factor $Q_m$ value of the NKN ceramics depended upon the KCN content and the sintering temperature. In particular, the KCN addition to the NKN greatly improved the mechanical quality factor $Q_m$ value. The ceramic with X = 2.0 mol% sintered at $1,150^{\circ}C$ possesses the optimum properties (${\varepsilon}_r=241$, $d_{33}=78$, $k_p=0.34$ and $Q_m=1,121$). These results indicate that the ceramic is a promising candidate material for applications in lead free piezoelectric transformer and filter materials.

• 대한의생명과학회지
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• 제11권3호
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• pp.355-363
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• 2005

This study aimed to investigate the cerebroprotective effect of vascular endothelial growth factor (VEGF) on permanent focal cerebral ischemia in Sprague-Dawley rats. Right middle cerebral artery (MCA) was occluded for 6 and 24 hours by an intraluminal monofilament technique. An open cranial window was made on the right parietal bone for determination of continuous changes in regional cerebral blood flow (rCBF) by laser-Doppler flowmetry. The infarct size was morphometrically determined using the 2,3,5-triphenyltetrazolium chloride technique. Brain edema was determined by measuring brain water content. In normal rats, rCBF was significantly increased by intravenous infusion of VEGF for 10 minutes. The VEGF-induced increase in rCBF was significantly inhibited by pretreatment with suramin, a heparin-binding growth factor inhibitor as well as $N^{\omega}-nitro-L-arginine$, a nitric oxide synthase inhibitor. In focal cerebral ischemic rats, the amplitude of decrease in rCBF during ischemic period was significantly less in VEGF-treated group, compared with that in vehicle-treated group. The cerebral infarct size was reduced by VEGF in a dose-dependent manner. The brain edema formation was dose-dependently reduced by VEGF in 24-hour MCA occlusion group but not in 6-hour MCA occlusion group. It is suggested that VEGF not only improves the rCBF during cerebral ischemic period but also reduces the brain edema formation, and thereby exert a protective effect on focal cerebral ischemia in rats.

• 국제지역연구
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• 제20권1호
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• pp.147-165
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• 2016

본 연구는 OECD 21개 국가의 패널 자료(1981~2011)를 활용하여 제2세대내생적성장이론의 실증적 타당성을 검정하였다. 모든 변수들이 비정상성을 지니므로 변수들 간의 공적분 검정을 수행한 결과 연구개발수준은 총요소생산성에 유의한 영향을 미친다는 준 내생적성장이론이 강력히 지지되는 반면, 완전한 내생적 성장이론에 따른 연구개발집약도와 총요소생산성 성장 간의 유의한 관계는 일부 모형에 국한하여 적합한 것으로 분석되었다. 총요소생산성성장 함수 추정 결과 국내 및 국외 연구개발수준의 증가는 총요소생산성에 모두 유의한 영향을 미치는 것으로 나타났으나, 연구개발집약도의 경우는 일부 모형에서만 국내 및 국외 연구개발집약도가 총요소생산성에 유의한 영향을 미치는 것으로 나타나 준 내생적 성장이론이 강하게 지지되었다. 다만 국가 간의 기술격차는 총요소생산성 격차를 줄이는 효과가 있는 것으로 분석되어 완전한 내생적 성장이론의 기술격차가설은 타당한 것으로 나타났다. 이상의 분석결과를 바탕으로 준 내생적 성장이론적 관점에서 정책적 함의를 살펴보면 OECD 국가들의 경제는 총연구개발투자에 대한 생산성 체감의 가정이 타당하며, 따라서 지속적인 경제성장을 유지하기 위해서는 연구개발투자의 지속적인 증가가 수반되어야 한다는 시사점을 얻을 수 있다.

• 한국콘텐츠학회논문지
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• 제15권12호
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• pp.407-420
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• 2015

본 연구는 연구개발 직군의 실행공동체 영향요인이 공동체 활동 만족도와 조직 내 학습문화 활성화에 미치는 관계를 분석하고, 실행공동체의 성숙도에 따른 성숙 집단과 미성숙 집단의 비교를 통해 기업의 실행공동체 담당자들에게 연구개발 직군의 실행공동체 활성화를 위한 시사점을 제시하고자 했다. 이를 위해 선행연구를 토대로 실행공동체 영향요인을 개인요인, 상호작용요인, 지원요인, 환경요인으로 구성하고, 수집된 총 371개의 설문을 기반으로 분석을 실시했다. 연구결과 연구 개발 직군의 실행공동체 활동에 있어 개인요인, 상호작용요인, 지원요인은 만족도에 유의미한 영향을 미쳤으나 환경요인은 크게 영향을 미치지 않는 것으로 나타났다. 또한 실행공동체 만족도가 높을수록 학습문화 활성화에 긍정적 영향을 미치는 것으로 나타나 연구개발 직군의 실행공동체 활동 강화가 조직문화 개선에 도움을 줄 수 있음을 알 수 있었다. 특히 연구개발 직군의 경우 성숙도에 따른 집단차이가 크게 나타나지 않아 성숙도 보다는 실행공동체 내 상호작용 요인을 강화하는 것이 더욱 중요하다는 사실을 알 수 있다.

• Steel and Composite Structures
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• 제35권4호
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• pp.599-609
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• 2020

The tension-only braced frames (TOBFs) are widely used as a lateral force resisting system (LFRS) in low-rise steel buildings due to their simplicity and economic advantage. However, the system has poor seismic energy dissipation capacity and pinched hysteresis behavior caused by early buckling of slender bracing members. The main concern in utilizing the TOBF system is the determination of appropriate performance factors for seismic design. A formalized approach to quantify the seismic performance factor (SPF) based on determining an acceptable margin of safety against collapse is introduced by FEMA P695. The methodology is applied in this paper to assess the SPFs of the TOBF systems. For this purpose, a trial value of the R factor was first employed to design and model a set of TOBF archetype structures. Afterwards, the level of safety against collapse provided by the assumed R factor was investigated by using the non-linear analysis procedure of FEMA P695 comprising incremental dynamic analysis (IDA) under a set of prescribed ground motions. It was found that the R factor of 3.0 is appropriate for safe design of TOBFs. Also, the system overstrength factor (Ω₀) was estimated as 2.0 by performing non-linear static analyses.

• 한국기계가공학회지
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• 제20권5호
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• pp.111-120
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• 2021

A tractor is an agricultural machine that performs farm work, such as cultivation, soil preparation, loading, bailing, and transporting, through attached working implements. Farm work must be carried out on time per the growing season of crops. As a result, the reliability of a tractor's transmission is vital. Ideally, the transmission's design should reflect the actual load during agricultural work; however, configuring such a measurement system is time- and cost-intensive. The design and analysis of a transmission are, therefore, mainly performed by empirical methods. In this study, a tractor with a measurement system was used to measure the actual working load in the field. Its hydro-mechanical transmission was then analyzed using the measured load. It was found that the velocity factor, load distribution factor, lubrication factor, roughness factor, relative notch sensitivity factor, and life factor affect the gear strength of the transmission. Also, loading conditions have a significant influence on the reliability of the transmission. It is believed that transmission reliability can be enhanced by analyzing the actual load on the transmission, as performed in this study.

• 대한간호학회지
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• 제47권1호
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• pp.121-132
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• 2017

Purpose: In this study the reliability and validity of the Korean version of the Cancer Stigma Scale (KCSS) was evaluated. Methods: The KCSS was formed through translation and modification of Cataldo Lung Cancer Stigma Scale. The KCSS, Psychological Symptom Inventory (PSI), and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire - Core 30 (EORTC QLQ-C30) were administered to 247 men and women diagnosed with one of the five major cancers. Construct validity, item convergent and discriminant validity, concurrent validity, known-group validity, and internal consistency reliability of the KCSS were evaluated. Results: Exploratory factor analysis supported the construct validity with a six-factor solution; that explained 65.7% of the total variance. The six-factor model was validated by confirmatory factor analysis (Q (${\chi}^2/df$)= 2.28, GFI=.84, AGFI=.81, NFI=.80, TLI=.86, RMR=.03, and RMSEA=.07). Concurrent validity was demonstrated with the QLQ-C30 (global: r=-.44; functional: r=-.19; symptom: r=.42). The KCSS had known-group validity. Cronbach's alpha coefficient for the 24 items was .89. Conclusion: The results of this study suggest that the 24-item KCSS has relatively acceptable reliability and validity and can be used in clinical research to assess cancer stigma and its impacts on health-related quality of life in Korean cancer patients.

• 한국전기전자재료학회논문지
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• 제22권3호
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• pp.205-209
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• 2009

In this study, in order to develop the composition ceramics for lead-free ultrasonic motor, (1-x-0.09)$NaNbO_{3-x}BaTiO_3-0,09LiNbO_3$ ceramics were fabricated using a conventional mixed oxide process and their piezoelectric and dielectric characteristics were investigated according to the $BaTiO_3$ substitution. All the specimens showed orthorhombic phase structure without secondary phase, $BaTiO_3$ substitution enhanced density, dielectric constant(${\epsilon}_r$) and electromechanical coupling factor($k_p$), However, mechanical quality factor was deteriorated. Curie temperature of specimens was observed as about $380^{\circ}C$. At the $BaTiO_3$ substitution of 4 mol%, density, electromechanical coupling factor($k_p$), dielectric constant(${\epsilon}_r$) and piezoelectric constant($d_{33}$) of specimen showed the optimum value of $4.493g/cm^3$, 0.236, 175, 70 pC/N, respectively.

• Clinical and Experimental Pediatrics
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• 제48권11호
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• pp.1172-1178
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• 2005

목 적 : 소아 비만은 전세계적으로 증가하고 있는 추세이며, 신체적으로나 정신적으로 장애를 일으킨다. 특히 고혈압, 관상동맥질환, 당뇨병 등의 성인병이 문제가 되고 있다. 이에 비만 청소년에서 혈중 인슐린, 인슐린저항지수, 유리 지방산, IGF-I, IGFBP-3를 측정하였고, 심혈관 질환으로 진행할 수 있는 위험인자로 유용한지 알아보기 위해 본 연구를 실시하였다. 방 법 : 64명의 중등도 이상의 비만 청소년를 대상군으로 하였고, 같은 연령의 정상 청소년 20명을 대조군으로 하였다. 신장, 체중을 이용하여 비만도와 체질량지수를 산출하였고, 안정된 상태에서 수축기, 이완기 혈압을 측정하였다. 10시간 이상 금식 후 총 콜레스테롤, 중성지방, HDL 콜레스테롤, LDL 콜레스테롤, AST, ALT, 혈당, 인슐린, 유리지방산, IGF-I, IGFBP-3를 측정하였다. 결 과 : 인슐린은 비만군에서 $15.6{\pm}7.0{\mu}IU/mL$로 정상군보다 유의하게 높았고(P<0.01), 인슐린저항지수도 비만군에서 $64.6{\pm}31.6$으로 정상군보다 유의하게 높았다(P<0.01). IGF-I은 비만군에서 $498.1{\pm}122.2ng/mL$로 정상군보다 유의하게 높았고(P<0.05), IGFBP-3도 비만군에서 $3,777{\pm}4,721ng/mL$로 정상군보다 유의하게 높았다(P<0.05). 인슐린은 체질량지수(r=0.394), 비만도(r=0.304)와 양의 상관관계를 나타냈다. IGFBP-3는 비만도(r=0.419), 이완기 혈압(r=0.264), 체질량지수(r=0.247)와 양의 상관관계를 보였다. 인슐린저항지수는 체질량지수(r=0.595), 혈중 중성지방(r=0.515), 비만도(0.469)와 양의 상관관계를 나타냈다. 결 론 : 비만 청소년에서 혈중 인슐린, 인슐린저항지수, IGF-I, IGFBP-3가 증가하였다. 청소년 비만에서 이들 검사는 심혈관질환으로의 진행을 예측하는데 유용하리라 생각한다.